Ecophysiological response of cacao (Theobroma cacao cv. Criollo and cv. Trinitario) in a Southern Belizean rainforest agroforestry system across light regimes
Sheri A. Shiflett, Lenardo Ash, James Rotenberg, Jacob Marlin
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引用次数: 0
Abstract
Theobromacacao is a tropical crop of economic and cultural importance in Southern Belize. Cacao plants, like coffee, are commonly grown under shade trees to reduce physiological stress affecting plant longevity. However, few studies have explicitly compared ecophysiological performance and plant stress responses of commonly cultivated varieties across a gradient of light. In this study, a suite of physiological responses linked to light-use (i.e., capture and processing) and plant stress among cacao agroforestry plants were investigated comparing multiple cultivars, wild-grown cacao, and cacao saplings exposed to a light gradient from full sun to nurse-plant shaded. Comparisons between cultivars demonstrated that ‘Trinitario’ performs similarly or higher than ‘Criollo’ as evidenced by similar photosynthetic rates relative to cultivated Criollo (6.3 ± 1.4 vs. 3.5 ± 1.3 μmol m−2 s−1) and higher linear electron flow rates than wild Criollo (58 ± 32 vs. 47 ± 34 μmol e− m−2 s−1), though at the trade-off of more physiological stress. For example, the photochemical reflectance index of Trinitario was higher compared to cultivated Criollo (0.02 ± 0.007 vs. 0.04 ± 0.01). Mature agroforestry-grown Criollo cacao and wild grown Criollo showed similarities for both light-use and stress responses. Cacao plants grown under nurse-plant shaded conditions exhibited reduced light-use and stress responses relative to those grown under partial- to no shade. Across cacao stands, increased light capture and processing was coupled with increased plant stress, and reduced leaf temperatures were associated with reduced plant stress. These results reinforce the importance of shade optimization for sustainable cacao agroforestry.
期刊介绍:
Agroforestry Systems is an international scientific journal that publishes results of novel, high impact original research, critical reviews and short communications on any aspect of agroforestry. The journal particularly encourages contributions that demonstrate the role of agroforestry in providing commodity as well non-commodity benefits such as ecosystem services. Papers dealing with both biophysical and socioeconomic aspects are welcome. These include results of investigations of a fundamental or applied nature dealing with integrated systems involving trees and crops and/or livestock. Manuscripts that are purely descriptive in nature or confirmatory in nature of well-established findings, and with limited international scope are discouraged. To be acceptable for publication, the information presented must be relevant to a context wider than the specific location where the study was undertaken, and provide new insight or make a significant contribution to the agroforestry knowledge base